logx(y)=-2,则y=1/x^2y>0,x>0,x!=1x+y=x+1/x^2设f(x)=x+1/x^2f'(x)=1-2/x^3在极大值点处导数为0f'(x)=0得x=2^(1/3)f(x)=2^(1/3)+2^(-2/3)=(3/2)*2^(1/3)即x+y的最小值为(3/2)*2^(1/3)